Gelcasting is a new method for forming advanced ceramics based on obtaining intermediary gels promoted by polimerization “in situ” within the ceramic slurry. Gelcast composites of an ALCOA A-1000 alumina and the copolymer obtained using acrylamide and N,N′-metylene-bisacrylamide as monomers were characterized by thermogravimetry. Polymer distribution was determined by thermogravimetric analysis of small size specimens that were taken from different parts of the alumina composites formed in different shapes. Derivative thermogravimetry was used to identify the resulting polymerization stage within the gelcast body, as well as to study the influence of mold materials and operating conditions. All the composites show an even distribution of the polymer in the bulk, which enables machining in the green state and obtaining high density alumina bodies after sintering.
In the present paper the effect of the thermoexfoliated graphite (EG) content (0–0.310 parts by volume), constituent mixing
conditions (a paddle mixer or a disk-and-screw extruder), annealing and aging on thermodestruction processes of polypropylene
(PP)/exfoliated graphite composite materials (CM) by means differential thermal analysis and the thermogravimetric method
have been investigated. The studies have shown that thermodestruction processes in CM based on PP and EG ran in air for expense
of PP thermodestruction. The characteristics of thermodestruction in CM essentially depend on a regime of making and concentration
of components. It is established that processes leading to the formation of less perfect crystalline structures or causing
amorphization of PP (including formation of continuous space structures from EG particles, cluster traps) advances thermodestruction.
The increase in crystallinity extent of PP favors to the decrease in thermodestruction processes.
Conducting polyaniline/Cobaltosic oxide (PANI/Co3O4) composites were synthesized for the first time, by in situ deposition technique in the presence of hydrochloric acid (HCl)
as a dopant by adding the fine grade powder (an average particle size of approximately 80 nm) of Co3O4 into the polymerization reaction mixture of aniline. The composites obtained were characterized by infrared spectra (IR)
and X-ray diffraction (XRD). The composition and the thermal stability of the composites were investigated by TG-DTG. The
results suggest that the thermal stability of the composites is higher than that of the pure PANI. The improvement in the
thermal stability for the composites is attributed to the interaction between PANI and nano-Co3O4.
Polyaniline/multi-walled carbon nanotube (PANI/MWNT) composites were prepared by in situ polymerization. Transmission electron
microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) were used to characterize the PANI/MWNT composites.
Thermal stability and glass transition temperature (Tg) were measured by thermogravimetry (TG) and temperature modulated differential scanning calorimetry (TMDSC), respectively.
The TG and derivative thermogravimetry (DTG) curves indicated that with augment of MWNTs content, the thermal stability of
PANI/MWNT composites increased continuously. While, Tg increased and then decreased with the MWNTs content increasing from 0 to 20 mass%.
and X-ray investigations were carried out on different building composites
in order to examine their relative hydration processes. The presence of lime,
hemihydrate gypsum, ferosilicate, and some other wastes as leaner and hydrophobic
additive in different proportions into composites provokes hydration reactions,
leading to calcium silicate hydrate (CSH), ettringite and an intermediate
phase formation with varying chemical composition of calcium, aluminum, silicon
DTA curves indicate several transformations taking
place between composites components, related to hydration of some phases.
The content of ettringite component corresponds to the properties and it is
used as an indicator for the possibility of industrial application. It is
found out that gypsum based cementitious binders could be used as building
material in the industry. The same time it is confirmed that the selected
wastes could be considered as secondary raw materials.
Three-phase cyanate ester adhesives have been developed using a bisphenol E cyanate ester resin, fumed silica, and negative-CTE
(coefficient of thermal expansion) reinforcements: short carbon fiber or zirconium tungstate (ZrW2O8). Fumed silica was used to impart thixotropic behavior on the resin and decrease settling in the adhesives. The cured composites
were evaluated using various thermal analysis techniques for their thermal-mechanical properties.
Composites with short carbon fiber showed enhanced modulus and decreased thermal expansion (70% reduction for 20 vol%) and
showed little phase separation. While settling of the dense ceramic particles could not be completely eliminated for the zirconium
tungstate composites through rheological modification of the adhesive with added fumed silica, a reduction in CTE of 84% was
achieved in the composite (58 vol%) compared to the neat resin. In addition, the effect of thermal history on the cure and
temperature induced ZrW2O8 phase transitions, and their corresponding influence on thermal strains vs. temperature, are examined by thermomechanical analysis.
Authors:C. Mothé, C. de Araujo, M. de Oliveira, and M. Yoshida
Polyurethane composites with bagasse of sugar cane (BSC) at different proportions: 5, 10 and 20 mass/mass% were prepared by
melt mixing method. The thermal behavior of these composites were studied by thermogravimetry (TG/DTG). The influence of fiber
concentration on the kinetic parameters of the composites was studied and a better interaction was suggested between PU/BSC
with 5mass/mass% of fiber. Scanning electron microscopy was carried out to investigate surface morphology.
Authors:Shaoxu Wang, Zihang Huang, Jianhai Wang, Yansheng Li, and Zhicheng Tan
Over the last few years, polyaniline (PANI) composites have been studied with growing interest because of their numerous applications in various electrical and electronic devices. Many articles on PANI
technique for the treatment of wastewater. The adsorption process is primarily focused on the use of activated carbon as adsorbent, due to large surface area and predominant proportion of mesopores [ 26 ]. Nowadays, composite materials specially
Geopolymers —X-ray-amorphous inorganic polysialates [ 1 – 5 ] are cementitious composites, which are commonly produced by idiosyncratic wet copolymerization (i.e., synthesis via solution) of the individual alumina and silica components [ 1 – 14 ]. Such a room